Cylinder barrel construction



A. v. D. WILLGOOS 2,301,235

CYLINDER BARREL CONSTRUCTION Nov. 10, 1942.

2 Sheets-Sheet 2 Filed Dec. 10, 1940 YINVENTOR flIdI'BulVH ATTORNEY.

Patented Nsvtm, 1942' r 1 2 5 UNITED STATES PATENT orrica I crmmsa :iNsranc'rroN Anommnwng mmnu mcmn signer to Uni Hartford, Conn, a corporation of Delaware Application December 10, 1940, Serial m. 309,45; 1: Claims. (01.123-171) This invention relates to improvements in enll generally indicates a cylinder head made sine cylinders and has particular reference to an separately from the barrel and preferably of improved engine cylinder having separate cylinsome light weight material of good heat conductder barrel, head, and barrel iln portions. ing properties, such as an aluminum alloy. This An object of the invention resides in the pro- 5 head is assembled with the outer end of the vision of an engine cylinder of the character inbarrel II by means of a screw thread construcdicated having an improved attachment means tion including the spring thread, generally indibetween thecylinder head and the cylinder cated at It. barrel. In the construction illustrated, the cylinder A further object resides in the provision of an barrel is provided with an integral annular atimproved engine cylinder'of the character inditaching flange ll below which is a skirt portion cated having an improved head attaching means 20 adapted to extend .within a crankcase (not arranged to facilitate the assembly of the barrel illustrated) to which the cylinder is attached. fin portion on the barrel'and obviate the neces- The cylinder barrel extends above the flange is sity of a thickened-barrel portion within the to provide a combustion chamber and'a working finned area. v space for an engine piston (not illustrated). A

Other objects and advantages will be more spiral groove 22 having a generally partly circular particularly pointed out hereinafter or will becross-sectional shape is formed in the exterior come apparent as the description proceeds. surface of the barrel it somewhat spaced from In the accompa ying drawings. in which like the upper-or outer end of the barrel and the reference numerals are used to designate similar spring thread It is threaded into this groove to parts throughout, there is illustrated by way of provide a screw thread for the attachment of example a suitable construction arrangement for the head I 4. As is clearly illustrated in Fig. 4, the purpose of disclosing the invention. The this spring thread has a cross-sectional shape drawings, however, are for the purpose of illus- 25 such that the inner portion thereof is partly tration only and are not to be taken as limiting circular to fit the groove 22 and the outer portion or restricting the invention since it. will be apis wedge shaped to provide a tapered screw thread parent to those skilled in the art that various fitting the internal screw threads provided in the changes in the illustrated construction may be annular portion of e head It.

resorted to without in any way exceeding the This thread arrangement per se is in comscope of the invention. mercial use for such elements as bolts, spark In the drawings, plugs, etc., and one such commercial product is Fig. 1 is a longitudinal sectional view of an known to the aircraft engine industry as the engine cylinder constructed according to the in- Aero thread vention. a The fin muifcomprises a continuous cylindrical derbarrelandabarrelflnmuflassembledthere- 4o nularflnsll. I

Fig. 2 is an elevational .view on an enlarged inner portion the inner surface of. which is scale of a spring thread forming a part ofthe shaped to fit closely about the outer surface of cylinder head attaching means. the barrel ll between the groove 22 and the Fig. 3 is an enlarged sectional view of a cylinflange II. and carries, a plurality of integral anwit-hand Ifdesired,themufll2maybeshrunkontothe is a sectional view on an enlarged scale portion of the cylinder bone] which it' overlies, of a'fragmentary portion of the cylinder barrel and if desired orconsid'ered necessary a bond of/ 1 Figs. 1 and 3- showing the application some suitable soldering or brazing material may theretoof the spring thread illustrated in Fig. 2.- be incorporated between the inner surface or; the

Referring tothe drawingsin detaih'thenumeral cylindrical portion a and the external airrse of ll generally indicates a cylinder barrel preferthe cylinder barrels to provide a ,heat transfer ably formedrof steel or-scme-similar strong and bond between the barrel and the muilll As it is resilient material. The numeral I: semi-m usuallynotdesirabletohave the barrelflnsconindicatesabarrelflnmnifwhichmsybeformed time dcwntothe flange I. the barrel maybe 01 aluminum, or some similarmateriai of good provided withan external annular shoulder is heatoonducting ancterisdnthe spaeedabcve'theflangelssndformin anab tintermediatcportimdthecylinderbarreillto -mentforthelowerendcfthemudilandtne 2 upper end of the mui! I! to clamp the mufl? in position between the head and the shoulder I0.

It is obvious that in the construction illustrated, the only way in which the mufi I! can be brought toits assembled position with respect to the barrel in is by inserting the upper or outer end or the barrel through the mud and moving the mufl! relative to the barrel until it reaches its final position against the abutment 30. It the muff has a shrink fit on thebarrel it will be heat expanded before assembly so that relative movement between the muff and the barrel may take place. A predetermined thickness of the cylinder barrel wall between the bottom of the groove 22 structural strength to maintain the head H in place on the barrel. This thickness, as indicated by the dimension a on Fig. 4, has a certain limiting value regardless of whether the head retaining threads are integral with the barrel or whether a separate spring thread is used. Furthermore, the inner surface of the barrel must be kept straight as indicated by the line 32 in Fig. 4. This means threads were normal V threads and were: made integral with the barrel the thickness of the mud receiving portion of the cylinder wall would have to be increased over the thickness indicated, by the or by the amount that the threads protruded beyond the straight wall thickness d. The additional thickness, as indicated by the dimension d in Fig. 4'-is not necessary for, cylinder barrel strength'at the location of the fin mud and would add materially to the weight of the cylinder barrel besides obstructing the free how of heat from the interior the fin mufi. By utilizing the spring thread i6 and the spiral groove 22-it is possible to limit the thickness of the mufi receiving portion of the barrel to the maximum thickness or the groove receivingportion's of the barrel and omit from the mud receiving portion the barrel thickness indicated by the dimension d. With this illustrated arrangement the mufi maybe assembled with the barrel before thespring thread I6 is assembled. After the mull has been brought 1 to its operative position against the abutment the spring thread l8 may be threaded into the spiral grooves 22 to provide an external thread for the head ll. After'the spring thread is in place the head ll may be heat expanded and threaded upon the spring thread I6 to its operative position against the upper or outer end of thefinmufl l2.

v The use or the spring thread It for retaining the head on the barrel has an additional advantage in that the groove 22 can be given a very shallow rounded cross-sectional shape obviating any relatively sharp edged out in the exterior surface of the barrel, which would lead to a concentration of stresses when the compression -and explosion forces within the cylinder tends to separate the head from the barrel. Because of this arrangement either the factor of safety, of the head attachment can be increased, or the wall thickness of the entire barrel can be somewhat decreased to provide a light weight barrel of ample'strength. Y

While an assembly method has been mentioned which suggests the threading or the spring thread .onto' the barrel and a subsequent threading of the cylinder head onto the threaded barrel, this and the inner surface ofv the barrel is required to provide the necessary.

that if the head retaining dimension D in Fig. 4, to the thickness indicated by the dimension 0 in that figuresurface of the barrel to the invention ating mufl surrounding and in -01 said cylinder barrel, and

' in said head does not mean that other methods might not b employed such as first threading the spring thread into the head and subsequently threading the head onto the barrel around the groove 22. While a suitable mechanical arrangement for the purpose of disclosing the invention has been illustrated in the accompanying drawing and hereinabove described, it is to be understoodthat is not limited to the particular arrangement so illustrated and described, but

that such changes in the size, shape and arrangement of the various parts may be resorted .to as come within the scope of the sub-joined claims.

Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows:

1. An engine cylinder comprising, a barrel, a tin mud overlying a portion of said barrel, a head having -a portion overlying a different portion of said barrel, and a spiral thread member operatively included between the overlapping portions of said head and said barrel, said barrel having a substantially uniform wall thickness throughout the portions included in said fin mufi and said head portion, and a thread groove of generally rounded cross section in the head included portion thereof.

2. The combination of an engine cylinder bar-. rel, a separate fin mufi shrunk onto the intermediate portion of said barrel, a cylinder head shrunk onto one end portion of said barrel, and a separate spiral member engaging in spiral grooves in the overlapping portions of said barrel and said head for securing said head on said barrel.- v

3. An engine larged portion at one end thereof, a heat radiclose heat conintermediate portion grooves in the other end of said barrel having a depth less than a normal V thread for receiving a spiral thread forming member.

4. In a cylinder barrel adapted to have a head screw threaded onto an end thereof and whose external diameter is determined by the internal diameter of a muff that is assembled with the barrel by passing it over the threaded portion of said barrel, a spiral groove located at said ducting relation with the end and having a depth less than a normal V site end of said barrel, said screw threads comprising a loose spiral member received in grooves and received in grooves in said barrel, the grooves in said barrel being of less depth than said head grooves, the grooved and muff-receiving portions of said cylinder having substantially the same outside diameter.

6. In combination, a steel cylinder barrel having an enlargement at one end, a separate heat radiating muff of light material having high heat transfer properties, and shrunk onto an intermediate portion of said barrel, and an aluminum head shrunk and screw threaded onto said barrel, 'said screw thread comprising a separate spiral member received in grooves in said head and said barrel, the intermediate portion or said .barrel which receives the mud being of smaller cylinder barrel. having an'endiameter than the outside diameter of the said separate thread when in place'on the barrel.

7. In an engine cylinder having a. flanged por- ANDREW V. D. WILLGOOS. 

